.Iadd.This is a reissue of U.S. Pat. No. 5,287,956, issued Feb. 22, 1994. .Iaddend.The present invention relates to conveyors driven by a drive shaft extending along the conveyor.
The primary type of driveshaft-driven conveyor used in the industry uses O-rings, which wrap around spools mounted on the drive shaft and around the conveyor rollers in order to drive the rollers as the drive shaft rotates. This type of conveyor has a speed limitation, because the O-rings may begin to slip at high speeds. It also is difficult to replace the O-rings when they break. It is also very difficult to stop portions of the O-ring driven conveyor for accumulation.
Some conveyors are known which use a drive shaft and drive by a means other than O-rings. For example, it is known to put a gear on the driveshaft and a gear on the conveyor roller and have a direct drive from the driveshaft to the roller. This arrangement cannot be put into the accumulation mode, because, whenever the driveshaft is rotating, all the conveyor rollers are rotating.
Chain-driven roller conveyors are known, but they also have speed limitations, can be very noisy, and require substantial maintenance. Chain-driven conveyors are not readily reversible in direction, because a chain must always be pulled, not pushed.